Groundwater quality assessment and modeling utilizing water quality index and GIS in Kabul Basin, Afghanistan

Groundwater stands as a unique source of water supply in Kabul city, Afghanistan. In this investigation, 35 samples of groundwater were comprehensively analyzed to determine its hydrogeochemical characterizations, quality, water types, and its acceptability as drinking sources. A portable digital multiparameter instrument (LAB MAN Scientific instrument) was used to measure the total dissolved solids (TDS), hydrogen potential (pH), and electrical conductivity (EC). Total hardness, chloride, and bicarbonate were examined via a titrimetric approach. Sodium, calcium, magnesium, and potassium concentrations were measured with a flame photometer. Fluoride was determined by using a digital portable multiparameter. UV-VIS spectrophotometers were employed to count sulfate and nitrate concentrations. The distribution pattern of measured parameters and the Water Quality Index (WQI) in groundwater were spatially modeled utilizing the ArcGIS tool. The findings provide insight into the main anions and cations, which are found in ascending sequence F < NO₃ < SO₄ < Cl < HCO₃ and K < Ca < Na < Mg, respectively. Based on the measurements of ion concentrations, bicarbonate (71.4%), chloride (14.28%), nitrate (2.85%), magnesium (80%), sodium (82.85%), calcium (5.71%), and potassium (17.14%) were all determined to be over the World Health Organization (WHO) limits of drinking water. Using the Piper trilinear diagram, two significant hydrochemical facies (CaNaHCO₃ and NaHCO₃) were discovered. Based on the mathematical model of WQI outputs, 88.57% of the research region has excellent to good water, whereas 11.43% has poor to very poor water.